Digital data recording apparatus, digital data recording method, and computer-readable recording medium

ABSTRACT

A data communication unit receives encrypted digital data via a network and records the digital data on a primary recording medium. The digital data, having been encrypted in different encryption methods according to the distributors, include attribute information indicating the encryption methods. The encryption method of the digital data is determined and the encrypted data is decrypted by an appropriate decryption unit. Identification information of a secondary recording medium or a playback apparatus is obtained according to whether the secondary recording medium is removable from the playback apparatus. A controller selects an encryption unit among a plurality of encryption units according to the obtained identification information. The selected encryption unit creates an encryption key according to the identification information and re-encrypts the digital data. A recording unit records the digital data on the secondary recording medium. An accounting unit charges according to accounting information in the attribute information.

This application is a continuation application of Ser. No. 10/916,523,filed Aug. 12, 2004 now U.S. Pat. No. 7,380,139, which is a divisionalapplication of Ser. No. 09/358,820, filed Jul. 22, 1999, which is nowU.S. Pat. No. 6,834,348.

This application is based on application Ser. Nos. 10-206967 and10-289831 filed in Japan, the contents of which are hereby incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital data recording apparatus, adigital data recording method, and a computer-readable recording mediumfor protecting the copyrights of digital data.

2. Description of the Related Art

Thanks to the recent widespread use of the Internet, distribution ofmusic with so-called EC (Electronic Commerce) has been developed, inwhich desired music data is downloaded from a homepage using a PC(Personal Computer) and the bill for the downloaded music data ischarged to a credit card, for instance. The widespread use of musicdistribution through the Internet using the EC (herein after referred to“electronic music distribution” in this specification) would reduce thenecessity for consumers to go to record stores and might drasticallychange the distribution of music, which has been mainly distributed byCDs (Compact Discs).

However, many people listen to music not only at home but also on theirway to the office, school, home, and in a car by using a portableplayback apparatus and the like. In these cases, music data must berecorded on a portable medium such as an MD (Mini Disc).

Regarding electronic music distribution, delivery companies adopt avariety of encryption methods to protect copyrights. More specifically,a different optimum encryption method is adopted according to themanufacturing company, the distribution route, the usage pattern, andthe like. Under these circumstances, when music data that has beendistributed through an electronic music distribution system is recordedon an MD, the playback apparatus is required to decode the music data onthe MD according to the adopted encryption method. As a result, theplayback apparatus is bulky, expensive, and not useful for users.

It is useful for users when music data that has been distributed throughan electronic music distribution system is decoded at the time ofrecording on an MD since playback apparatuses can be inexpensive.

In this case, however, unauthorized duplication of music data isencouraged, and as a result, the copyright of the music data cannot befully protected.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a digitaldata recording apparatus, a digital data recording method, and acomputer-readable recording medium for protecting copyrights andreproducing music data that are recorded on a recording medium with aninexpensive digital data playback apparatus.

The above-mentioned object may be achieved by a digital data recordingapparatus for recording digital data on a recording medium, where thedigital data recording apparatus may include: a communication unit forreceiving encrypted digital data via a digital network; a decryptionunit for decrypting the encrypted digital data that has been received bythe communication unit; an encryption unit including a plurality ofencryption sub-units which each re-encrypt decrypted digital data inencryption methods that have different security levels; a recording unitfor recording digital data that has been re-encrypted by the encryptionunit on the recording medium; and a controller for controlling thedecryption unit and the encryption unit; wherein the controller causesone of the plurality of encryption sub-units to re-encrypt the digitaldata that has been decrypted by the decryption unit.

As a result, it is possible to record digital data that has beenre-encrypted by the encryption unit and that can be easily reproduced bythe playback apparatus. It is also possible to protect the copyright ofthe digital data since the digital data has been re-encrypted.

The above-mentioned object may be also achieved by the digital datarecording apparatus, wherein the digital data that has been recorded onthe recording medium is reproduced by a playback apparatus. Further, theencryption unit includes a first encryption sub-unit for re-encryptingdigital data by using an encryption key that has been created accordingto identification information of the recording medium, and a secondencryption sub-unit for re-encrypting digital data by using anencryption key that has been created according to identificationinformation of the playback apparatus. The controller determines whetherthe recording medium is removable from the playback apparatus, causesthe first encryption sub-unit to re-encrypt the decrypted digital datawhen the recording medium is removable from the playback apparatus, andhas the second encryption sub-unit re-encrypt the decrypted digital datawhen the recording medium is not removable from the playback apparatus.

As a result, when the digital data on a recording medium is reproducedby a playback apparatus, the digital data may be reproduced byre-encrypting the digital data by using an encryption key that has beencreated according to the identification information of the recordingmedium. On the other hand, when the digital data on a recording mediumis reproduced by a specific playback apparatus, the digital data may bereproduced by the specific playback apparatus by re-encrypting thedigital data by using an encryption key that has been created accordingto the identification information of the specific playback apparatus.

The above-mentioned object may be also achieved by the digital datarecording apparatus which may also include an accounting unit forconducting an accounting process via the digital network, wherein thecontroller determines an accounting value according to an encryptionsub-unit that has re-encrypted the decrypted digital data, and controlsthe accounting unit so that the controller conducts the accountingprocess according to the determined accounting value.

As a result, it is possible to select an encryption sub-unit from amongthe plurality of encryption sub-units that re-encrypt digital data inencryption methods having different security levels, and it is possibleto pay a charge according to the selected encryption sub-unit.

The above-mentioned object may be also achieved by the digital datarecording apparatus, wherein the controller prohibits the decryptionunit from decrypting the encrypted digital data when the encryption unitfails to create any encryption key.

As a result, an unnecessary decryption of digital data may be preventedwhen the encryption unit fails to create any encryption key.

The above-mentioned object may be also achieved by the digital datarecording apparatus, wherein the security levels of the encryptionmethods in which the plurality of encryption sub-units re-encryptdecrypted digital data are lower than security levels of encryptionmethods in which encrypted digital data that are to be received by thecommunication unit have been encrypted.

As a result, a playback apparatus may easily reproduce digital data,thereby leading to a less expensive playback apparatus.

The above-mentioned object may be also achieved by the digital datarecording apparatus, wherein: the encrypted digital data that isreceived by the communication unit has been encrypted in one of theencryption sub-systems having different security levels and theencrypted digital data includes attribute information that indicates theencryption system; the decryption unit includes a plurality ofdecryption sub-units that decrypt the encrypted digital data that havebeen encrypted in the encryption systems; and the controller determinesthe encryption system in which the encrypted digital data has beenencrypted according to the attribute information, and controls thedecryption unit so that a decryption sub-unit from among the pluralityof decryption sub-units corresponding to the determined encryptionsystem decrypts the encrypted digital data.

As a result, even when received digital data have been encrypted inencryption systems having different security levels, it is possible todecrypt the digital data by selecting a decryption sub-unit according tothe encryption system in which the digital data has been encrypted.

The above-mentioned object may be also achieved by the digital datarecording apparatus, which may further include an accounting unit forconducting an accounting process via the digital network, wherein thecontroller determines an accounting value according to a decryptionsub-unit that has decrypted the encrypted digital data and an encryptionsub-unit that has re-encrypted the decrypted digital data, and thecontroller controls the accounting unit so that the controller conductsthe accounting process according to the determined accounting value.

As a result, it is possible to pay a charge according to the decryptionand re-encryption of digital data and to protect the copyright.

The above-mentioned object may be also achieved by a digital datarecording method of recording digital data on a recording medium, wherethe digital data recording method may include: a communication step forreceiving encrypted digital data via a digital network; a decryptionstep for decrypting the encrypted digital data that has been received atthe communication step; an encryption step for re-encrypting decrypteddigital data in one of a plurality of encryption systems havingdifferent security levels; and a recording step for recording digitaldata that has been re-encrypted at the encryption step on the recordingmedium.

As a result, it is possible to record digital data on a recording mediumthat has been re-encrypted in an encryption system so that the digitaldata is easily reproduced by a playback apparatus. In addition, sincethe digital data is re-encrypted, the copyright of the digital data maybe protected.

The above-mentioned object may be also achieved by the digital datarecording method, wherein the encrypted digital data that is received atthe communication step has been encrypted in an encryption system amonga plurality of encryption systems having different security levels, andwhere the encrypted digital data includes attribute information thatindicates the encryption system. In addition, the digital data recordingmethod may further comprise a determining step for determining one ofthe plurality of encryption systems according to the attributeinformation, wherein the decryption step decrypts the encrypted digitaldata according to the determination of the determining step.

As a result, digital data that has been recorded on a recording mediummay be reproduced by any playback apparatus or only by a specificplayback apparatus.

The above-mentioned object may be also achieved by a computer-readablerecording medium that is applied to a digital data recording apparatusfor recording digital data on a first recording medium, where thecomputer-readable recording medium stores a program that causes acomputer to execute: a communication step for receiving encrypteddigital data via a digital network; a decryption step for decrypting theencrypted digital data that has been received at the communication step;an encryption step for re-encrypting decrypted digital data in anencryption system among a plurality of plurality of encryption systemshaving different security levels; and a recording step for recordingdigital data that has been re-encrypted at the encryption step on therecording medium.

As a result, it is possible to record digital data on a recording mediumthat has been re-encrypted in an encryption system so that the digitaldata is easily reproduced by a playback apparatus. In addition, it ispossible to protect copyrights by using the recording medium in adigital data recording apparatus that does not have a function toprotect copyrights.

The above-mentioned object may be also achieved by the computer-readablerecording medium, wherein the encrypted digital data that is received atthe communication step has been encrypted in an encryption system amongthe plurality of encryption systems having different security levels,and where the encrypted digital data includes attribute information thatindicates the encryption system. In addition, the digital data recordingmethod may further include a determining step for determining anencryption system among the plurality of encryption systems according tothe attribute information.

As a result, it is possible to reproduce digital data that has beenrecorded on the first recording medium by any playback apparatus or by aspecific apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the presentinvention will become apparent from the following description when takenin conjunction with the accompanying drawings, which illustrate specificembodiments of the present invention. In the Drawings:

FIG. 1 shows the structure of a digital data recording apparatusaccording to a first embodiment of the present invention;

FIG. 2 is an external view of the hardware configuration of the firstembodiment of the present invention, and an external view of a playbackapparatus of a recording medium according to the first embodiment of thepresent invention;

FIG. 3 shows an example of a display screen of a home page forpurchasing music data according to the first embodiment of the presentinvention;

FIG. 4 shows an example of the data structure of music data that isdownloaded on a primary recording medium according to the firstembodiment of the present invention;

FIG. 5 shows an example of a display screen of a home page forpurchasing music data according to the first embodiment of the presentinvention;

FIG. 6 is a first flowchart illustrating the operations in the firstembodiment of the present invention;

FIG. 7 is a second flowchart illustrating the operations in the firstembodiment of the present invention;

FIG. 8 shows the structure of a digital data recording apparatusaccording to a second embodiment of the present invention;

FIG. 9 is an example of information that is displayed on a display unitwhen digital signals provided by the information provider are recordedin the second embodiment;

FIG. 10 is a flowchart showing the operations in the second embodiment;

FIG. 11 shows the structure of a digital data recording apparatusaccording to a third embodiment of the present invention;

FIG. 12 shows the attribute information of data in the third embodiment;

FIG. 13 is a flowchart showing operations in the third embodiment;

FIG. 14 is a flowchart showing operations in the third embodiment;

FIG. 15 shows the structure of the digital data recording apparatusaccording to a fourth embodiment of the present invention;

FIG. 16 shows the structure of a digital data recording apparatusaccording to a sixth embodiment of the present invention;

FIG. 17 is an example of attribute information;

FIG. 18 shows an example of management information;

FIG. 19 is a flowchart showing operations in the sixth embodiment;

FIG. 20 shows the structure of a playback apparatus for reproducingdigital data that has been recorded in the sixth embodiment;

FIG. 21 is a flowchart showing operations by the digital data playbackapparatus in the sixth embodiment;

FIG. 22 shows the structure of a digital data recording apparatusaccording to a seventh embodiment of the present invention;

FIG. 23 shows an example of the data structure of attribute informationthat is attached to digital data when the digital data is transmitted inseventh embodiment;

FIG. 24 is a flowchart showing operations in seventh embodiment;

FIG. 25 shows an example of the data structure of attribute informationthat is attached to digital data when transmitted in another example ofthe seventh embodiment.

DETAILED DESCRIPTION OF THE INVENTION

A detailed explanation of the preferred embodiments of a digital datarecording apparatus according to the present invention will be givenwith reference to the drawings.

First Embodiment

FIG. 1 shows the structure of a digital data recording apparatusaccording to a first embodiment of the present invention. The digitaldata recording apparatus includes a data transmit/receive unit(communication unit) 100, a reception unit 101, a primary recordingmedium 102, a data extraction unit 103, a judging unit 104, a decryptionunit group 105, an encryption method designation unit (controller) 109,an encryption unit group 110, a secondary recording medium 114, arecording unit 115, an inherent information obtaining unit 116, adesignation reception unit 117, and an accounting unit 118.

Note that each element of the digital data recording apparatus, exceptfor the secondary recording medium 114 and the recording unit 115, isgenerally realized by a PC (Personal Computer) 201, as shown in FIG. 2.The recording unit 115 is realized by, for instance, a DVD (DigitalVersatile Disc)-RAM drive 202, and the secondary recording medium 114 isrealized by a DVD-RAM disc 203.

The digital data recording apparatus receives music data, i.e.,encrypted digital data that is distributed through the Internet, anddownloads the received music data in the primary recording medium 102.Then, the digital data recording apparatus decodes the digital data inthe decryption unit group 105, re-encrypts the decoded digital data inthe encryption unit group 110, and records the re-encrypted digital datain the secondary recording medium 114.

Note that although an explanation of electronic music distribution willbe given in the first embodiment, the type of distributed digital datais not limited to music. Distributed digital data may be video data,character data, or the combination of those kinds of data.

The data transmit/receive unit 100 is a communication unit which isrealized by a modem and a control software, and the datatransmit/receive unit 100 is connected to the host computer (notillustrated) of an information provider through a telephone line. Whenthe data transmit/receive unit 100 is informed of the purchaserequirement of a piece of music that has been received by the receptionunit 101 via the data extraction unit 103, the data transmit/receiveunit 100 transmits the purchase requirement to the host computer. Thedata transmit/receive unit 100 downloads music data from the hostcomputer according to the purchase requirement via the Internet, andrecords the downloaded music data in the primary recording medium.Meanwhile, the data transmit/receive unit 100 transmits accountinginformation to the host computer that has been generated at the time themusic is purchased.

Next, an explanation of information that is provided by the informationprovider will be given. The information provider sets up a site, i.e., ahomepage for the sale of music data, to provide information such asmusic titles and prices that are necessary for users to purchase musicdata and which may arouse the interest of users. Users purchase desiredmusic data according to the information that is provided by theinformation provider.

FIG. 3 shows an example of a homepage for the sale of music dataprovided by an information provider. The information includes titles301, singers 302, times 303, and prices 304. A title 301 and a singer302 show the title and singer of one piece of music data. A time 303shows the time required to record (play back) one piece of music data,and a price 304 shows the selling price of one piece of music data. Auser selects a piece of music according to the information, and the userinforms the data transmit/receive unit 100 of a purchase requirementthrough the reception unit 101. Needless to say, the informationprovided by the information provider is not limited to characterinformation as shown in FIG. 3. For example, the information may beimages such as jacket pictures and music data for test-listening.

The reception unit 101 includes a keyboard and a mouse, and receives apurchase requirement from the user who has watched the information shownin FIG. 3 on the display screen of the PC. The received purchaserequirement is transferred to the data transmit/receive unit 100 via thedata extraction unit 103.

The primary recording medium 102 is realized by a hard disk in the PC,and stores the music data, i.e., the encrypted digital data that hasbeen received by the data transmit/receive unit 100. Meanwhile, in asecure area on the primary recording medium 102, encrypted accountinginformation, for instance, is recorded by the accounting unit 118 whenthe downloaded music data is recorded on the secondary recording medium114.

FIG. 4 shows an example of the data structure of downloaded music datathat is stored in the primary recording medium 102, i.e., music datathat the information provider provides. Music data that is provided bythe information provider is mainly composed of attribute information 401including the title, singer and the price of the music data, and a musicdata unit 402 that is the music data itself.

The attribute information 401 includes ISRC (International StandardRecording Code) information 403, a title 404, a singer 405, a price 406,an information provider 407, and an encryption format 408. Anexplanation of the attribute information 401 will be given below.

The ISRC information 403 is specific information assigned to each pieceof music data, and is composed of a country code (two ASCII (AmericanStandard Code for International Interchange) characters), an owner code(three ASCII characters), a recording year (two-digit numbers), and aserial number (five-digit numbers). The title 404 is characterinformation showing the title of the music data, and the singer 405 ischaracter information showing the singer of the music data. The price406 is information showing the monetary amount for the music data. Notethat the price 406 shows the amount that is charged when the downloadedmusic data is recorded on the secondary recording medium 114 by usingthe digital data recording apparatus in the first embodiment.

The information provider 407 is information showing the provider or thecopyrighter of the music data, i.e., the information provider 407 showsthe recipient of the amount that is charged when the user records themusic data by using the digital data recording apparatus.

The encryption format 408 is information showing the encryption formatin which the downloaded music data has been encrypted, because theencryption format of music data depends on the information provider. Forinstance, when information providers A, B, and C each provide musicdata, music data provided by the information provider A is encrypted ina format A, music data provided by the information provider B isencrypted in a format B, and music data provided by the informationprovider is encrypted in a format C. Note that the main object of thepresent invention in the first embodiment is to convert data on thesecondary recording medium 114 according to an encryption format that iseasily decoded by a playback apparatus and to protect the copyright wheninformation that is provided by information providers are encrypted in avariety of formats. As a result, a detailed explanation of the algorithmof encryption will not be given herein.

In the attribute information 401, the price 406 and the informationprovider 407 are encrypted as necessary since the tampering of the price406 and the information provider 407 can lead to a pecuniary orproprietary loss to the information provider.

When the data extraction unit 103 receives an instruction from theencryption method designation unit 109 to extract digital data, the dataextraction unit 103 extracts the attribute information 401 from theprimary recording medium 102 and informs the accounting unit 118 of theattribute information 401. Meanwhile, the data extraction unit 103informs the judging unit 104 of information in the encryption format408. Note that when the price 406 is encrypted in the attributeinformation 401, the data extraction unit 103 informs the accountingunit 118 of the price 406 after the decoding by the decryption unitgroup 105. Then, the data extraction unit 103 extracts the music dataunit 402 from the primary recording medium 102, and outputs theextracted music data unit 402 to the judging unit 104. As has beendescribed, the data extracted by the data extraction unit 103 has beenencrypted using an encryption method that is specific to the informationprovider.

The judging unit 104 is informed of the encryption format 408 by thedata extraction unit 103. Then, the judging unit 104 judges to whichdecryption unit of the decryption unit group 105 the music data is to beoutput according to the information of the encryption format 408.

The decryption unit group 105 includes “n” decryption units, where “n”is an integer greater than one. A first decryption unit 106 decodesdigital data that has been encrypted in the format A, a seconddecryption unit 107 decodes digital data that has been encrypted in theformat B, and an “n”th decryption unit 108 decodes digital data that hasbeen encrypted in the format N. Each of the first, second, and nthdecryption units 106, 107, and 108 is composed of the decode module of adifferent information provider.

For instance, when the information of the encryption format 408indicates the format B, the judging unit 104 outputs the digital data inthe music data unit 402 of the music data to the second decryption unit107. The second decryption unit 107 decodes the inputted digital dataand outputs the decoded digital data to the encryption methoddesignation unit 109.

When a decryption key is necessary to decrypt encrypted data by one ofthe first, second, and nth decryption units 106, 107, and 108, the datatransmit/receive unit 100 obtains a decryption key according to theencryption method of the data so as to decrypt the data. The first,second, and nth decryption units 106, 107, and 108 once decrypt the datathat has been encrypted using a different encryption method according tothe information provider.

When the encryption system designation unit 109 receives the designationof the type of the encryption method from the designation reception unit117, the encryption method designation unit 109 instructs the inherentinformation obtaining unit 116 to obtain inherent information accordingto the designation of the encryption method. When the encryption methoddesignation unit 109 is notified of the inherent information by theinherent information obtaining unit 116, the encryption methoddesignation unit 109 instructs the data extraction unit 103 to extractmusic data. When the encryption method designation unit 109 is notifiedthat the inherent information according to the designation of theencryption method cannot be obtained by the inherent informationobtaining unit 116, the encryption method designation unit 109 showsthat the designated encryption method cannot be used to re-encrypt dataon the display unit (not illustrated). On the other hand, when theencryption method designation unit 109 does not receive the designationof the type of the encryption method from the designation reception unit117, the encryption method designation unit 109 instructs the inherentinformation obtaining unit 116 to obtain inherent information accordingto the attribute of the secondary recording medium 114. When theencryption method designation unit 109 receives the notificationconcerning the obtainment of the inherent information of the secondaryrecording medium 114 from the inherent information obtaining unit 116,the encryption method designation unit 109 instructs the data extractionunit 103 to extract music data. When the encryption method designationunit 109 is notified that the inherent information of the secondarymedium 114 cannot be obtained, the encryption method designation unit109 generates random numbers.

When having received the designation of the kind of encryption methodfrom the designation reception unit 117, the encryption methoddesignation unit 109 selects one encryption unit according to thedesignation. When the encryption method generation unit 109 receives theinput of decrypted digital data from one of the first, second, nthdecryption units 106, 107, and 108, the encryption method designationunit 109 notifies the selected encryption unit of the decrypted digitaldata along with the inherent information that the encryption methodgeneration unit 109 has been informed of by the inherent informationobtaining unit 116.

When the encryption method designation unit 109 does not receive thedesignation of the type of the encryption method from the designationreception unit 117, the encryption method designation unit 109 selectsone encryption unit according to the type of the inherent informationthat the encryption method designation unit 109 has been informed of bythe inherent information obtaining unit 116. When the encryption methoddesignation unit 109 receives the input of the decrypted digital datafrom one of the first, second, nth decryption units 106, 107, and 108,the encryption method designation unit 109 notifies the selectedencryption unit of the digital data and the inherent information. On theother hand, when the encryption method designation unit 109 receives thenotification that the inherent information cannot be obtained from theinherent information obtaining unit 116, the encryption methoddesignation unit 109 notifies one of the encryption units of the digitaldata along with the generated random numbers.

The encryption unit group 110 includes “n” encryption units, which are afirst, second, . . . , “n”th encryption units 111, 112, . . . , 113.Each of the encryption units 111, 112, . . . , 113 re-encrypts thedigital data of which each of the encryption units have been informed ofby the encryption system designation unit 109 with a differentencryption key, respectively. More specifically, the first encryptionunit 111 re-encrypts data with an encryption key that is createdaccording to the identification information which is inherent in thesecondary recording medium 114. The second encryption unit 112re-encrypts data with an encryption key that is created according to theidentification information that is inherent in a playback apparatus (notillustrated) for playing back the secondary recording medium 114. Thenth encryption unit 113 re-encrypts data with an encryption key that iscreated according to random numbers. Each of the data sizes of theencryption keys is set to be smaller than the data size of theencryption key of encrypted digital data that is recorded on the primaryrecording medium 102.

When the data size of the encryption key of re-encrypted digital datathat is to be recorded on the secondary recording medium recordingmedium 114 is relatively small, the digital data is decrypted relativelyeasily. As a result, the structure which is necessary to decrypt thedigital data of a playback apparatus for playing back the digital datais simple, thereby leading to a reduced cost for the playback apparatus.

For instance, when the encryption method designation unit 109 does notreceive an instruction from the designation reception unit 117 and whenthe encryption method designation unit 109 is informed of theidentification information of the secondary recording medium 114 fromthe inherent information obtaining unit 116, the encryption methoddesignation unit 109 informs the first encryption unit 111 of theidentification information of the secondary recording medium 114. Thefirst encryption unit 111 creates an encryption key according to theinformed identification information, rewrites the encryption format 408of the attribute information 401 of the music data that the firstencryption unit 111 has been informed of by the encryption systemdesignation unit 109, and re-encrypts the music data unit 402 by usingthe created encryption key. The first encryption unit 111 informs therecording unit 115 of the re-encrypted digital data.

When the encryption method designation unit 109 receives the instructionto re-encrypt data using the inherent information of a playbackapparatus (not illustrated) for playing back the secondary recordingmedium 114 from the designation reception unit 117, the encryptionmethod designation unit 109 instructs the inherent information obtainingunit 116 to obtain the identification information which is inherent inthe playback apparatus. When the encryption method designation unit 109is informed of the identification information which is inherent in theplayback apparatus from the inherent information obtaining unit 116, theencryption method designation unit 109 informs the second encryptionunit 112 of the informed identification information and the decrypteddigital data that the encryption method designation unit 109 has beeninformed of from the decryption unit group 105.

The second encryption unit 112 creates an encryption key according tothe identification information that has been transferred from theencryption method designation unit 109, re-encrypts the digital datawith the created encryption key, and informs the recording unit 115 ofthe re-encrypted digital data. As in the case where the encryptionmethod designation unit 109 does not receive the instruction from thedesignation reception unit 117, the content of the encryption format 408in the attribute information 401 is rewritten.

The secondary recording medium 114 is composed of a DVD-RAM disc (shownin FIG. 2), an MD, and a small-scale semiconductor memory that is eitherremovable or non-removable according to the model of a playbackapparatus (not illustrated) and the like. Music data that has beenre-encrypted by the encryption unit group 110 is recorded on thesecondary recording medium 114 by the recording unit 115. For instance,when digital data has been recorded on the DVD-RAM disc 203, the DVD-RAMdisc 203 is inserted into the DVD-Audio player 204 so as to play music,as shown in FIG. 2.

The recording unit 115 is realized by, for instance, the DVD-RAM drive202 shown in FIG. 2. The recording unit 115 records digital data thathas been transferred from the encryption unit group 110 on the secondaryrecording medium 114. When the recording unit 115 completes recording,the recording unit 115 informs the accounting unit 118 of thecompletion.

When the inherent information obtaining unit 116 is instructed to obtainthe identification information which is inherent in the secondaryrecording medium 114 by the encryption system designation unit 109, theinherent information obtaining unit 116 reads the information written inthe BCA (Burst Cutting Area), and informs the encryption methoddesignation unit 109 of the read information when the secondaryrecording medium 114 is a DVD-RAM, for instance. Note that eachsecondary recording medium 114 has a different piece of inherentidentification information that has been recorded at the time ofmanufacturing, and as a result, the identification information cannot beread or rewritten by an ordinary user operation.

An encryption key is created according to the identificationinformation, and digital data that is re-encrypted with the encryptionkey is recorded on a DVD-RAM disc. As a result, even if a user with amalicious intent makes a copy of the content of the DVD-RAM disc onanother recording medium by using a tool for a bit copy and tries toplay back the copied data on other recording media, the copied datacannot be normally decrypted since the information corresponding to thedecryption key of the other recording medium is different from that ofthe DVD-RAM disc. In this way, the copyright of the music data is fullyprotected.

Meanwhile, when the inherent information obtaining unit 116 isinstructed by the encryption method designation unit 109 to obtain theidentification information which is inherent in the playback apparatus(not illustrated) in which the secondary recording medium 114 is placedtherein the inherent information obtaining unit 116 reads theidentification information of the playback apparatus and informs theencryption method designation unit 109 of the read identificationinformation. Each playback apparatus also has a different piece ofinherent identification information that has been assigned at the timeof manufacturing, and as a result, the identification information cannotbe read or rewritten by an ordinary user operation. Therefore, when datais re-encrypted according to identification information, there-encrypted data can be played back only by a particular playbackapparatus.

Note that when the inherent information obtaining unit 116 cannot obtainthe inherent identification information that has been designated by theencryption method designation unit 109, i.e., when no identificationinformation is assigned to the secondary recording medium 114 and theplayback apparatus, the inherent information obtaining unit 116 informsthe encryption method designation unit 109 that the designated inherentidentification information cannot be obtained.

When the inherent information receiving unit 116 receives theinstruction to obtain inherent identification information without theinstruction of the type of the inherent identification information, theinherent information obtaining unit 116 judges (determines) whether thesecondary recording medium 114 is either a recording medium that isremovable from the playback apparatus such as a DVD-RAM disc or arecording medium that is built in the playback apparatus such as asmall-scale semiconductive memory. When the secondary recording medium114 is a removable recording medium, the inherent information obtainingunit 116 reads the inherent identification information of the secondaryrecording medium 114, and informs the encryption method designation unit109 of the read inherent identification information. On the other hand,when the secondary recording medium 114 is a non-removable recordingmedium, the inherent information obtaining unit 116 reads the inherentidentification information of the playback apparatus, and informs theencryption method designation unit 109 of the read inherentidentification information. When identification information cannot beobtained, the inherent information obtaining unit 116 informs theencryption method designation unit 109 that identification informationcannot be obtained.

The designation reception unit 117 is realized by the keyboard and themouse of the PC. The designation reception unit 117 receives theinstruction of the type of the encryption method from the user, andinforms the encryption method designation unit 109 of the type of theencryption method.

While the homepage information in FIG. 3 shows only one type of price,the homepage information in FIG. 5 shows two types of price, i.e., aprice (1) 501 and a price (2) 502.

While the price (1) 501 shows the price when digital data isre-encrypted at the time of recording according to the identificationinformation which is inherent in the secondary recording medium 114, theprice (2) 502 shows the price when digital data is re-encrypted at thetime of recording according to the identification information which isinherent in the playback apparatus for playing back the secondaryrecording medium 114. Note that each of the prices (1) 501 and (2) 502is freely set by the information provider.

The user specifies the encryption of the digital data in a desiredencryption format with reference to the music and price informationshown in FIG. 5 according to the usage pattern of the secondaryrecording medium 114 by using the designation reception unit 117. Forinstance, when digital data is to be played back in a specific playbackapparatus, i.e., when the secondary recording medium 114 is not playedback in other playback apparatuses, the user specifies that the digitaldata be re-encrypted according to the identification information whichis inherent in the specific playback apparatus. As shown by the price(2) in FIG. 5, prices are generally cheap when data is re-encryptedaccording to the identification information of the playback apparatus.This is because the degree of freedom is low as compared with theencryption according to the identification information which is inherentin the secondary recording medium 114 since re-encrypted data is notplayed back in other playback apparatuses. When digital data is to beplayed back with any playback apparatus, the user specifies that thedigital data be re-encrypted according to the identification informationwhich is inherent in the secondary recording medium 114.

Note that although the designation reception unit 117 is integral withthe reception unit 101, the designation reception unit 117 and thereception unit 101 are described as separate elements for a convenientexplanation.

The accounting unit 118 receives the notification of the attributeinformation 401 of music data from the data extraction unit 103, andstores the received attribute information 401. When the accounting unit118 is notified that re-encrypted digital data is recorded on thesecondary recording medium 114 by the recording unit 115, the accountingunit 118 refers to the price 406 in the attribute information 401 so asto determine the charged amount, and writes the determined amount ofcharge along with the attribute information 401 in a secure area on theprimary recording medium 102 as the accounting information.

Note that when the price 406 includes the prices (1) 501 and (2) 502 asshown in FIG. 5, the charged amount is determined according to one ofthe first to nth encryption units 111 to 113 that has been transferredto the accounting unit 118 as the used encryption unit from theencryption method designation unit 109.

Here, an explanation of the operations in the first embodiment will begiven with reference to the flowcharts in FIGS. 6 and 7.

The reception unit 101 receives a home page requirement from the user,the data transmit/receive unit 100 accesses a homepage that is providedby an information provider of music data, and the data extraction unit103 displays a homepage (refer to FIGS. 3 and 5) on the display unit(not illustrated) (step s602).

The data extraction unit 103 waits for an instruction to purchase musicdata that is designated by the user from the reception unit 101, andinstructs the data transmit/receive unit 100 to receive the designatedmusic data (step s604). When the data transmit/receive unit 100 receivesthe music data, the data transmit/receive unit 100 downloads thereceived music data on the primary recording medium 102 (s606).

Watching the homepage display, the user inputs the type of theencryption method according to the usage pattern of the secondaryrecording medium 114 by using the designation reception unit 117.

The encryption method designation unit 109 determines whether thedesignation reception unit 117 has informed the encryption methoddesignation unit 109 of the designation of the type of the encryptionmethod (step s608). When the encryption method designation unit 109 isinformed of the designation of the type of the encryption method, theencryption method designation unit 109 instructs the inherentinformation obtaining unit 116 to obtain the inherent information thatis to be used for the designated type of the encryption method of (steps610). The encryption method designation unit 109 determines whether theinherent information obtaining unit 116 has informed that the inherentinformation cannot be obtained (step s612). When the encryption methoddesignation unit 109 is informed that the inherent information cannot beobtained, the encryption method designation unit 109 has the displayunit (not illustrated) display that the music data cannot bere-encrypted according to the designated type of the encryption method(step s614) so as to complete the processing. On the other hand, whenthe encryption method designation unit 109 is informed of the inherentinformation for the designated type of the encryption method, theencryption method designation unit 109 instructs the data extractionunit 103 to extract the digital data. Then, the data extraction unitextracts the music data recorded on the primary recording medium 102(step s616).

In step s608, when the encryption method designation unit 109 determinesthat the designation reception unit 117 has not informed the encryptionmethod designation unit 109 of the designation of the type of theencryption method, the encryption method designation unit 109 instructsthe inherent information obtaining unit 116 to obtain inherentinformation without designating the type of the inherent information(step s618).

The inherent information obtaining unit 116 determines the attribute ofthe secondary recording medium 114, i.e., determines whether thesecondary recording medium 114 in the playback apparatus (notillustrated) is a removable recording medium. When the secondaryrecording medium 114 is a removable recording medium, the inherentinformation obtaining unit 116 obtains the identification information ofthe secondary recording medium 114. However, when the secondaryrecording medium 114 is a non-removable recording medium, the inherentinformation obtaining unit 116 obtains the identification information ofthe playback apparatus (step s620).

When the encryption method designation unit 109 is informed of theinherent (identification) information by the inherent informationobtaining unit 116, or when the encryption method designation unit 109is informed that inherent information has not been obtained (step s622),the encryption method designation unit 109 instructs the data extractionunit 103 to extract the digital data. The processing then advances tostep s616.

Then, in step s702, the judging unit 104 refers to the encryption format408 in the attribute information 401 of the music data that has beenextracted by the data extraction unit 103 and determines which one ofthe first to nth decryption units 106 to 108 in the decryption unitgroup 105 decrypts the music data.

The decryption unit among the first to nth decryption units 106 to 108,as determined by the judging unit 104, decrypts the digital data thathas been input via the judging unit 104, and outputs the decrypteddigital data to the encryption method designation unit 109 (step s704).

The encryption method designation unit 109 selects an encryption unitfrom among the first to nth encryption units 111 to 113 in theencryption unit group 110 according to the inherent information that hasbeen transferred from the inherent information obtaining unit 116(including the information indicating that inherent information cannotbe obtained), and the encryption method designation unit 109 informs theselected encryption unit of the inherent information (generated randomnumbers in the case where the information indicates that inherentinformation cannot be obtained) and the decrypted digital data (steps706).

The informed encryption unit among the first to nth encryption units 111to 113 creates an encryption key according to the inherent(identification) information (according to the random numbers in thecase of the information of the random numbers), and re-encrypts thedigital data by using the created encryption key. At this time, thecontent of the encryption format 408 is rewritten in the attributeinformation 401 (step s708).

The recording unit 115 records the digital data that has beentransferred from one of the first to nth encryption units 111 to 113 onthe secondary recording medium 114 (step s710). When the recording unit115 completes the recording, the recording unit 115 informs theaccounting unit 118 of the recording completion.

When the accounting unit 115 receives the information from the recordingunit 115, the accounting unit 118 determines the charged amountaccording to the price 406 and the like that has been transferred fromthe data extraction unit 103, and records the charged amount on theprimary recording medium 102 (step s712) so as to complete theprocessing.

In the first embodiment, the decryption unit group 105 are composed ofthe decryption modules (the first to nth decryption units 106 to 108)each for different information providers. The decryption unit group mayinclude different decryption units according to the quality of musicdata, for instance, for digital data in 24 bits of LPCM (Liner PulseCode Modulation), MP3 (Moving Picture Experts Group 1 Audio Layer 3) andthe like. More specifically, while high quality 24 bits of LPCM may beset as encrypted digital data that is difficult to decrypt, normal MP3may be set as encrypted digital data that is not so difficult todecrypt, and the first decryption unit 106 may decrypt digital data in24 bits of LPCM and the second decryption unit 107 may decrypt digitaldata in MP3.

In the first embodiment, the encryption unit group 110 includes thefirst to nth encryption units 111 to 113 each for different kinds ofinherent information. The encryption units may correspond to the qualityof music data. More specifically, digital data that has been decryptedby the first decryption unit 106 may be re-encrypted by the firstencryption unit 111, digital data that has been decrypted by the seconddecryption unit 107 may be re-encrypted by the second encryption unit112, and digital data that has been decrypted by the nth decryption unit108 may be re-encrypted by the nth encryption unit 113. In this case,the data size of the encryption key used for encryption in the firstencryption unit 111 is larger than the data size of the encryption keyused in the second encryption unit 112, and the data size of theencryption key used in the second encryption unit 112 is larger than thedata size of the encryption key used in the nth encryption unit 113. Theaccounting unit 118 determines the accounting amount of digital dataaccording to the decryption unit that has decrypted the digital data andthe encryption unit that has re-encrypted the digital data. As a result,the higher the quality of digital data, the more surely the copyright isprotected. In this case, the information provider may set higher pricefor music data with higher quality.

The digital data recording apparatus according to the first embodimenthas the structure shown in FIG. 1. It is possible to record a program ona computer-readable recording medium such as a floppy disk that has acomputer realize the functions of the elements of the digital datarecording apparatus, and to protect copyrights by applying the computerreadable recording medium to a digital data recording apparatus that hasno function of protecting copyrights.

In the first embodiment, digital data is downloaded from the hostcomputer when the user requires the purchase of the digital data. It ispossible to temporarily record music data or only the attributeinformation on the primary recording medium in the PC of the userregardless of the purchase, and to purchase digital data that has beenrecorded on the primary recording medium 102.

While the attribute information 401 and the music data unit 402 areseparately described in the first embodiment, the attribute information401 may be embedded in the digital data in the music data 402 by usingWater Mark (electronic watermark) technology.

In the first embodiment, the data input and output between thedecryption unit group 105 and the encryption unit group 110 via theencryption method designation unit 109 has not been referred to inparticular. For security purposes is possible to prevent the leakage ofdecrypted data by transmitting data after authentication or by realizingthe decryption unit group 105, the encryption method designation unit109, and the encryption unit group 110 with one chip.

In addition, while accounting information is recorded in a secure areaon the primary recording medium 102 in the first embodiment, accountinginformation may be recorded on another recording medium such as an ICcard.

No explanation of the timing of accounting has been given in the firstembodiment. It is possible to suppose that the modem is connected to thehost computer when digital data is recorded on the secondary recordingmedium 114, to suppose that the modem is automatically connected to thehost computer when the amount of charge reaches to a set amount, or tosuppose that the modem is connected to the host computer when a setperiod of time has elapsed since the recording of accountinginformation.

In addition, while it has been described that only audio information isprovided by the information provider in the first embodiment, videoinformation, audio information, character information, the combinationof video information, audio information, and character information, andthe like may be provided.

Second Embodiment

FIG. 8 shows the structure of a digital data recording apparatusaccording to a second embodiment of the present invention. The digitaldata recording apparatus of the second embodiment is generally realizedby a personal computer. The digital data recording apparatus of thesecond embodiment includes a data transmit/receive unit 2101, a primaryrecording medium 2102, a data extraction unit 2103, an encryption methodjudging unit 2104, a first decryption unit 2105, a second decryptionunit 2106, a third decryption unit 2107, an encryption unit 2108, arecording unit 2109, a secondary recording medium 2110, an input unit2111, a display unit 2112, and a recording medium inherent informationobtaining unit 2113. While a decryption unit group 2115 is composed ofthe first, second and third decryption units 2105, 2106 and 2107, thenumber of decryption units in the decryption unit group 2115 is notlimited to three. The decryption unit group 2115 is composed of aplurality of decryption units.

Note that data to be recorded in the second embodiment are music datathat are distributed through the Internet. The music data are supposedto be encrypted using different encryption methods according to therespective providers.

An information provider provides music data and information whichincludes music titles, prices, copy control information, and the like(herein after referred to as “attribute information” in thisspecification) that are necessary at the time of purchase and which mayarouse the interest of users together or separately. In the secondembodiment, the attribute information and music data are supposed to beseparately provided.

The data transmit/receive unit 2101 is a communication unit that isrealized by a modem, and is connected to the host computer (notillustrated) of the information provider through a telephone line. Theattribute information that the data transmit/receive unit 2101 obtainsis recorded on the primary recording medium 2102, and the entireattribute information or a part thereof is displayed on the display unit2112. FIG. 9 is an example of the information that is displayed on thedisplay unit 2112. Information such as titles 2201, title codes 2202,singers 2203, and data sources 2204 are displayed. Here, a title 2201and a singer 2203 show the title and singer of one piece of music data,respectively. A title code 2202 is an identifier for distinguishing onepiece of music data from another piece of music data. A piece of ISRC(International Standard Recording Code) information is added to a titlecode 2202, for instance. According to the information, the user selectsa piece of desired music and transfers the purchase requirement via theinput unit 2111. A data source 2204 is a URL (Uniform Resource Locator)for specifying the location of a piece of music data. When ISRCinformation is added to a title code 2202, the data source can beidentified by the title code 2202.

The input unit 2111 is realized by a mouse, a keyboard, and the like.The input unit 2111 receives an instruction to purchase music, i.e., arecording instruction, and informs the data transmit/receive unit 2101of the instruction. The user clicks or designates the title and the likeof the selected music with the mouse according to the information thatis displayed on the display unit 2112 so as to provide an instructionfor the recording of the music data.

When the data transmit/receive unit 2102 receives the instruction torecord the music data, the data transmit/receive unit 2101 downloads thedesired music data from the host computer of the respective providerthrough the telephone line. At this time, the location of the music datais specified according to the URL in the attribute information. Themusic data downloaded is once recorded on the primary recording medium2102.

The primary recording medium 2102 is generally a hard disk in the PC,and records the desired music data without decrypting. As a result, thedigital data recording apparatus is not necessarily connected to thehost computer of the provider during the following operations.

The data extraction unit 2103 extracts the music data to be recordedfrom the primary recording medium 2102. At this time, the user selectsthe music data to be recorded on the secondary recording medium 2110with the input unit 2111 according to the information that is displayedon the display unit 2112, which is almost equivalent to the informationshown in FIG. 9. The data that is extracted by the data extraction unit2103 has been encrypted using an encryption method according to theinformation provider, and as a result, the encryption method judgingunit 2104 determines an appropriate system to decrypt the data. Forexample, information for identifying the encryption method of digitaldata is added to the header of the digital data, or the attributeinformation indicates the encryption method, and the encryption methodjudging unit 2104 determines the encryption data according to suchinformation.

The first, second, and third decryption units, 2105, 2106, and 2107 showthat digital data are decrypted in different methods according to theinformation providers. As described above, the number of decryptionunits is not limited to three. The encryption method judging unit 2104selects an appropriate decryption unit, and the selected decryption unitdecrypts the encrypted data. More specifically, the encryption methodjudging unit 2104 obtains or creates a decryption key corresponding tothe obtained encryption system of the data, and the selected decryptionunit decrypts the data with the obtained or created decryption key. As aresult, data that have been encrypted using different encryption methodare once decrypted.

The encryption unit 2108 re-encrypts the decrypted data. In the secondembodiment, information which is inherent in the recording medium issupposed to be used as the encryption key information at the time ofencryption. Note that a method of encryption according to informationwhich is inherent in a recording medium is described in JapaneseLaid-Open Patent Application No. 05-257816, so a detailed explanationwill not be given here.

The recording medium inherent information obtaining unit 2113 extractsthe inherent information from the secondary recording medium 2110according to an instruction from the encryption unit 2108, and transfersthe extracted inherent information to the encryption unit 2108.

The encryption unit 2108 re-encrypts data by using the inherentinformation that has been obtained by the recording medium inherentinformation obtaining unit 2113 as the encryption key.

Here, an explanation of the information which is inherent to thesecondary recording medium 2110 will be given.

Each secondary recording medium 2110 has a different inherentidentification information. When a secondary recording medium 2110 is aDVD-RAM, the inherent identification information is the informationwritten in the BCA (Burst Cutting Area). Each disc has a differentinformation in the BCA, and the information is recorded at the time ofmanufacturing and is not rewritable. As a result, even if a user with amalicious intent makes a copy of the content of the disc on anotherrecording medium by using a tool for a bit copy, the copied data cannotbe decrypted since the information corresponding to the decryption keyof the other recording medium is different from that of the disc. Inthis way, the copyright of the data is surely protected.

The recording unit 2109 records the re-encrypted data on the secondaryrecording medium 2110.

An explanation of the operations by the digital data recordingapparatus, the structure of which having been described, will be givenwith reference to the flowchart in FIG. 10.

The data transmit/receive unit 2101 downloads the attribute information(step s2301), and waits for an instruction from the user to recorddigital data (step s2302). The data transmit/receive unit 2101 downloadsthe designated digital data and records the digital data on the primaryrecording medium 2102 (step s2303). The encryption method of thedownloaded data is determined, and an appropriate decryption unit amongthe first, second, and third decryption units 2105, 2106, and 2107 isinstructed (designated) to decrypt the data (step s2304). The designateddecryption unit among the first, second, and third decryption units2105, 2106, and 2107 decrypts the data (step s2305). When the decrypteddata is input in to the encryption unit 2108 by the designateddecryption unit, the encryption unit 2108 obtains the inherentinformation of the secondary recording medium 2110 from the recordingmedium inherent information obtaining unit 2113 (step s2306). Anencryption key is created or obtained by using the obtained inherentinformation as part of the encryption key, and the encryption unit 2108re-encrypts the data (step s2307). The recording unit 2109 records there-encrypted data on the secondary recording medium 2110 (step s2308),and then, the processing is completed.

An explanation has been given of the digital data recording apparatusaccording to the second embodiment of the present invention.

An explanation of a digital data recording apparatus according to athird embodiment of the present invention will be given below.

Third Embodiment

FIG. 11 shows the structure of the digital data recording apparatusaccording to the third embodiment of the present invention. The digitaldata recording apparatus of the third embodiment is generally realizedby a PC. The digital data recording apparatus of the third embodimentincludes a data transmit/receive unit 2101, a primary recording medium2102, a data extraction unit 2103, an encryption method judging unit2104, a decryption unit group 2115, an attribute information obtainingunit 2401, a copy control information detection judging unit 2402, acopy control information conversion unit 2403, an accounting informationcalculation unit 2404, an encryption unit 2108, a secondary recordingmedium 2110, an input unit 2111, a display unit 2112, and a recordingmedium inherent information obtaining unit 2113.

Note that the elements of the digital data recording apparatus that arethe same in the second and third embodiments have the same referencenumbers and explanations of such elements are not given below.

FIG. 12 shows the attribute information of data in the third embodiment.The attribute information in FIG. 12 includes copy control information2501 and accounting information 2502 in addition to the attributeinformation shown in FIG. 9. The copy control information 2501 shows thenumber of times that the data can be recopied or copied. For instance,in terms of the number of times that the data can be recopied, a valuecorresponding to “no limit”, “copying only (no recopying)”, “no copying”and the like is shown. On the other hand, the number of times that thedata can be copied is an integer larger than “0”. More specifically, “norecopying” means that digital data that has been recorded on a secondaryrecording medium 2110 cannot be recopied. “No limit” means that the datacan be copied any number of times. The copying times, such as, “twocopies” means that data can be copied on two secondary recording media2110.

The attribute information obtaining unit 2401 obtains attributeinformation corresponding to the data to be reproduced from the primaryrecording medium 2102. In the third embodiment, the copy controlinformation and the accounting information 2502 are extracted from theattribute information by the copy control information detection judgingunit 2402 and the accounting information calculation unit 2404,respectively, as will be described below. Note that since the attributeinformation includes copyright protection information and the accountinginformation 2502, it is desirable to record the attribute information ina secure area on the primary recording medium 2102 so that the attributeinformation could not be accessed by an ordinary user operation.

The copy control information detection judging unit 2402 extracts thecopy control information from the attribute information so as to obtainthe information that indicates whether copying or recopying is allowedand the number of times that data can be copied or recopied.

When copying or recopying is allowed, the copy control informationconversion unit 2403 rewrites the copy control information as necessary.For instance, when recopying is prohibited, the copy control informationconversion unit 2403 changes the value of the copy control information2501 so that recopying would be prohibited. When the number of timesthat the data is copied is limited, the copy control informationconversion unit 2403 changes the value of the copy control information2501 by “1” so that the value recorded on the secondary recording medium2110 would be a number that is less than the allowed copying numberrecorded on the primary recording medium 2102.

When the allowed copying number is set, what is important is the numberof times that the data on the primary recording medium 2102 is recordedon the secondary recording medium 2110. The rewriting of the copycontrol information is to rewrite the copy control information valuethat is recorded on the primary recording medium 2102. As a result, theallowed copying number that has been recorded on the primary recordingmedium 2102 is decreased by “1”, and the allowed copying number that isto be recorded on the secondary recording medium is “0”.

The accounting information calculation unit 2404 obtains the accountinginformation of the desired music data from the attribute informationthat has been obtained by the attribute information obtaining unit 2401,calculates the charged amount according to the accounting information,and records the calculated charged amount in a secure area on theprimary recording medium 2102.

An explanation of the operations of the digital data recordingapparatus, the structure of which having been described, will be givenwith reference to the flowcharts in FIGS. 13 and 14.

First, the data transmit/receive unit 2101 downloads the attributeinformation (step s2601), waits for a recording instruction of thedigital data from the user (step s2602), downloads the designateddigital data, and records the downloaded digital data on the primaryrecording medium 2102 (step s2603). Then, the data transmit/receive unit2101 obtains the attribute information of the data to be recorded fromthe attribute information obtaining unit 2401 (step s2604). The copycontrol information detection judging unit 2402 determines the copycontrol information 2501 in the attribute information and determineswhether copying is allowed (step s2605). When copying is allowed, theallowed number of times of recopying or copying is obtained, and theobtained number of times is rewritten by the copy control informationconversion unit 2403 as necessary (step s2606). On the other hand, whencopying is not allowed, the processing is discontinued (step s2607).Then, the encryption method is determined, and an appropriate decryptionunit in the decryption unit group 2115 is instructed (designated) todecrypt the digital data (step s2608). The designated decryption unitamong the first, second, and third decryption units decrypts the digitaldata (step s2609). After the decryption, the charged amount iscalculated according to the accounting information that has beenobtained by the attribute information obtaining unit 2401 (step s2610).

When the encryption unit 2108 receives the decrypted data from thedesignated decryption unit, the encryption unit 2108 obtains theinherent information of the secondary recording medium 2110 from therecording medium inherent information obtaining unit 2113 (step s2611).An encryption key including the obtained inherent information as partthereof is created, and the encryption unit 2108 re-encrypts the data(step s2612). The recording unit 2109 records the re-encrypted data onthe secondary recording medium 2110 (step s2613), and the processing iscompleted.

Up to this point, an explanation of the third embodiment of the presentinvention has been given.

Fourth Embodiment

An explanation of a digital data recording apparatus according to thefourth embodiment of the present invention will be given. The digitaldata recording apparatus of the fourth embodiment is different from thedigital data recording apparatus in the second embodiment with respectto encryption key information and in that the digital data recordingapparatus of the fourth embodiment includes an inherent informationobtaining/transfer unit 2803, a recording unit 2109, and a secondaryrecording medium 2110 in a second digital data recording apparatus 2801.FIG. 15 shows the structure of the digital data recording apparatusaccording to the fourth embodiment of the present invention. The digitaldata recording apparatus of the fourth embodiment is composed of a firstdigital data recording apparatus 2800 and the second digital datarecording apparatus apparatuses 2800 and 2801.

The first digital data recording apparatus 2800 includes a datatransmit/receive unit 2101, a primary recording medium 2102, a dataextraction unit 2103, an encryption method judging unit 2104, adecryption unit group 2115, an encryption unit 2108, an input unit 2111,a display unit 2112, and an inherent information obtaining unit 2802.

The second digital data recording apparatus 2801 includes the inherentinformation obtaining/transfer unit 2803, the recording unit 2109, andthe secondary recording medium 2110.

Note that the elements of the digital data recording apparatus of thefourth embodiment that are the same in the second embodiment have thesame reference numbers and explanations of such elements are not givenbelow.

When the data that has been decrypted in the decryption unit group 2115is input into the encryption unit 2108, the inherent informationobtaining unit 2802 requires the inherent information obtaining/transferunit 2803 in the second digital data recording apparatus 2801 totransfer inherent information. The inherent informationobtaining/transfer unit 2803 obtains either the identificationinformation which is inherent in the secondary recording medium 2110 inthe second digital data recording apparatus 2801 or the identificationinformation which is inherent in the second digital data recordingapparatus 2801, and the inherent information obtaining/transfer unit2803 transfers the obtained identification information to the inherentinformation obtaining unit 2802.

The encryption unit 2108 creates an encryption key by using theidentification information which is inherent in the secondary recordingmedium 2110 in the second digital data recording apparatus, theidentification information which is inherent in the second digital datarecording apparatus 2801, or the combination of these identificationinformation, and the encryption unit 2108 re-encrypts the decrypteddata. The encryption unit 2108 outputs the re-encrypted data to thesecond digital data recording apparatus 2801. The recording unit 2109 inthe second digital data recording apparatus 2801 records there-encrypted data on the secondary recording medium 2110.

Note that the inherent information that is obtained and transferred bythe inherent information obtaining/transfer unit 2803 is theidentification information which is inherent in the second digital datarecording apparatus 2801 when the secondary recording medium 2110 isfixed in the second digital data recording apparatus 2801, and is theidentification information which is inherent in the secondary recordingmedium 2110 or the combination of the identification information whichis inherent in the second digital data recording apparatus 2801 and theidentification information inherent in the secondary recording medium2110 when the secondary recording medium 2110 is removable from thesecond digital data recording apparatus 2801. As a result, more flexibleencryption methods can be available.

Up to this point, an explanation of the fourth embodiment of the presentinvention has been given.

Fifth Embodiment

Here, an explanation of a digital data recording apparatus according toa fifth embodiment of the present invention will be given. The digitaldata recording apparatus of the fifth embodiment is almost the same asthose in the second, third, and fourth embodiments. The explanation ofthe digital data recording apparatus of the fifth embodiment will begiven with reference to the block diagram in FIG. 15 used in thedescription of the fourth embodiment. The digital data recordingapparatus of the fifth embodiment is different from the digital datarecording apparatus of the fourth embodiment with regard to adopting anencryption method corresponding to the secondary recording medium 2110at the time of recording. More specifically, since the minimum unit ofdata, or the unit of data amount at the time of writing encrypted data,is different for a DVD-RAM and a semiconductor memory, the inherentinformation obtaining unit 2802 obtains information of the particularmedium from the inherent information obtaining/transfer unit 2803 so asto re-encrypt data in a optimal unit of data. As a result, a pluralityof encryption units 2108 are included and inherent information andmedium information are transferred to an appropriate encryption unitamong the plurality of encryption units 2108. By doing so, not only aDVD-RAM but also a semiconductor memory, an IC card, and a hard disk canbe used as the secondary recording medium 2110.

Up to this point, an explanation of the fifth embodiment has been given.

Note that the second through fifth embodiments of the present inventionhave been explained as examples of a system by which optimal effects canbe expected under the present situation. The embodiments can be changedwithin the range of the basic principles of the present invention.Examples of changed embodiments will be given below.

In the second through fifth embodiments, digital data is downloaded fromthe host computer when the user requests to purchase the digital data.It is possible to record digital data on the primary recording medium2102 in the user's PC regardless of the purchase and to request topurchase digital data that has been recorded on the primary recordingmedium 2102.

In the second through fifth embodiments, copy control information isindicated in the attribute information. It is possible to embed copycontrol information into digital data by using Water Mark technology.

While it has been explained that the accounting information is recordedin a secure area on the primary recording medium 2102, it is possible toprovide another recording medium other than the primary recording medium2102 such as an IC card to record the accounting information.

While the information that is provided by the information provider isaudio information in the second through fifth embodiments, theinformation is not limited to audio information. The information can bevideo information, audio information, character information, or thecombination of video, audio, and character information.

Sixth Embodiment

FIG. 16 shows the structure of a digital data recording apparatusaccording to a sixth embodiment of the present invention.

The digital data recording apparatus of the sixth embodiment includes acommunication unit 3101, a recording medium 3102, a received datarecord/judging unit 3103, a display unit 3104, an input operation unit3105, a recording medium inherent information obtaining unit 3106, anencryption unit 3107, a recording unit 3108, an accounting informationrecording unit 3109, an accounting information recording medium 3110,and an accounting unit 3111. The digital data recording apparatus of thesixth embodiment is realized by a PC.

The communication unit 3101 is realized by a modem, and is connected tothe host computer (not illustrated) of a data provider and an accountingcenter (not illustrated) via a telephone line. When the communicationunit 3101 receives digital data and the attribute information from thehost computer, the communication unit 3101 informs the received datarecord/judging unit 3103 of the reception of the digital data and theattribute information.

When the communication unit 3101 receives an inquiry of the charge fromthe accounting center, the communication unit 3101 informs theaccounting unit 3111 of the inquiry. When the communication unit 3101 isinformed of accounting information by the accounting unit 3111, thecommunication unit 3101 informs the accounting center of accountinginformation via the telephone line.

Note that digital data provided by the data provider is supposed to bemusic data in the sixth embodiment. Music data to be provided issupposed to be encrypted digital data, and an information identifier issupposed to be added to a piece of digital data. The informationidentifier of a piece of music data is supposed to be the title code fordistinguishing the music from another piece of music data.

Attribute information is also supposed to be added to a piece of digitaldata. Attribute information includes information indicating the chargeand the provider of digital data.

FIG. 17 is an example of the attribute information. The attributeinformation 3201 includes titles 3202, performers (singers) 3203, titlecodes 3204, recording charges 3205, charges per reproduction 3206,maximum numbers of reproducing 3207, encryption conditions 3208, andcopy permissions 3209.

The titles 3202 and the performers 3203 are displayed on the displayunit 3104. The user indicates to copy (replicate) the digital dataaccording to the titles 3202 and the performers 3203. A title code isunique to a piece of music for distinguishing the music from anotherpiece of music. For instance, an ISRC is used as a title code 3204. Notethat the ISRC is composed of a country code (two ASCII characters), anowner code (three ASCII characters), a recording year (two-digitnumbers), and a serial number (five-digit numbers).

A recording charge 3205, a charge per reproduction 3206, a maximumnumber of reproducing 3207, and the like are included in accountingstandard data, and are information for calculating the charges of apiece of music data.

A recording charge 3205 indicates a charge when the digital data thathas been received by the communication unit 3101 is recorded on therecording medium 3102. A charge per reproduction 3206 indicates thecharge for each time the digital data that has been recorded on therecording medium 3102 is reproduced. A maximum number of reproducing3207 indicates the maximum number of times that the digital data thathas been recorded on the recording medium 3102 can be reproduced. Forinstance, when a maximum number of reproducing 3207 is “100”, thedigital data can be reproduced up to 100 times. Note that it is possibleto set a maximum number of reproducing 3207 so that no additional chargeis required after the number of reproducing reaches a certain number oftimes.

An encryption condition 3208 is a flag showing whether the digital datathat has been received by the communication unit 3101 is an encrypteddata.

A copy permission 3209 is a flag that is recorded by the user, and thecopy permission 3209 shows whether it is permitted to record music datathat has been received by the recording medium 3102. For instance, “onlyonce” indicates that the music data is permitted to be recorded onlyonce, and “permitted” indicates that the music data is permitted to berecorded any number of times.

Note that the main object of the present invention is to protect thecopyright of received music data when the music data is recorded(replicated) on the recording medium 3102, and therefore, an explanationof a case where it is only permitted to listen to music data will bebriefly given. In this case, the copy permission 3209 is “notpermitted”. While neither the decryption unit nor the input unit isincluded in the structure shown in FIG. 16, digital data that has beenreceived by the communication unit 3101 is decrypted by a decryptionunit so as to input music from an input unit. At this time, theaccounting standard data includes a listening charge.

The recording medium 3102 is composed of a rewritable storage elementsuch as a DVD-RAM, and is removable from the digital data recordingapparatus of the sixth embodiment.

Inherent information of the recording medium 3102 is recorded in advancein a non-rewritable secure area on the recording medium 3102.

The digital data that has been re-encrypted by the encryption unit 3107is recorded by the recording unit 3108 on the recording medium 3102.

In addition, the management information and attribute information of therecorded digital data are recorded on the recording medium 3102 by therecording unit 3108.

When the received data record/judging unit 3103 is informed of thedigital data and the attribute information 3201 from the communicationunit 3101, the received data record/judging unit 3103 stores theattribute information 3201, has the display unit 3104 display the title3202, the player 3203, the recording charge 3205, the charge perreproduction 3206 and the like, and informs the encryption unit 3107 ofthe digital data.

When the received data record/judging unit 3103 receives an instructionto copy (replicate) music, the received data record/judging unit 3103judges whether the digital data corresponding to the title code 3204 ofthe designated music can be copied by referring to the copy permission3209 of the attribute information. When the digital data can be copiedby the recording unit 3108, the received data record/judging unit 3103instructs the recording medium inherent information obtaining unit 3106to obtain the inherent information of the recording medium 3102, andinforms the encryption unit 3107 of the title code 3204 and theencryption condition 3208.

When the recording unit 3108 is not permitted to copy the digital data,the received data record/judging unit 3103 has the display unit 3104display that copying of the digital data is not permitted.

When the received data record/judging unit 3103 is notified that thedigital data has been copied by the recording unit 3108, the receiveddata record/judging unit 3103 rewrites the copy permission 3209 in thestored attribute information 3201. More specifically, when the copypermission 3209 is “only once”, the “only once” is changed to “notpermitted”. When the number of times of copying is greater than one, thenumber of times that copying is permitted is decreased by one. Note thatthe storage area for storing the attribute information 3201 is in theEEPROM (Electrically Erasable and Programmable ROM), and as a result,the storage content is not erased when the power of the digital datarecording medium is turned off.

For instance, when the received data record/judging unit 3103 isinformed of the completion of copying by the recording unit 3108 afterinforming the encryption unit 3107 of the title code 3204 “song01”, thereceived data record/judging unit 3103 changes the copy permission 3209corresponding to the title code “song01” from “only once” to “notpermitted”. As a result, any violation of the copyright of the dataprovider can be prevented.

The display unit 3104 is composed of a liquid crystal display or a CRT(Cathode-Ray-Tube). The display unit 3104 displays the title of themusic data (digital data), or the display unit 3104, indicates that thedigital data cannot be copied under the control of the received datarecord/judging unit 3103.

The input operation unit 3105 is composed of a mouse and the like. Theinput operation unit 3105 receives the user's instruction to copydigital data and informs the received data record/judging unit 3103 ofthe user's instruction. When downloading a piece of music upon referringto titles and players that are displayed by the display unit 3104, theuser clicks the title and the like with the mouse and instructs thecopying of the music.

When the recording medium inherent information unit receives aninstruction to obtain the inherent information from the received datarecord/judging unit 3103, the recording medium inherent informationobtaining unit 3106 reads the inherent information that has beenrecorded in a secure area on the recording medium 3102, and therecording medium inherent information obtaining unit 3106 informs theencryption unit 3107 of the read inherent information.

The encryption unit 3107 creates an encryption key according to theinherent information that has been received from the recording mediuminherent information obtaining unit 3106. The encryption unit 3107re-encrypts the digital data that has been received from the receiveddata record/judging unit 3103 by using the created encryption key, andinforms the recording unit 3108 of the re-encrypted digital data.

Note that when the encryption unit 3107 is informed that the digitaldata that has been received from the received data record/judging unit3103 has been encrypted, the encryption unit 3107 causes the digitaldata to be decrypted, or the encryption unit 3107 uses the digital datawithout a decryption.

More specifically, when the encryption unit 3107 is informed of digitaldata “data A”, which is to be recorded on the recording medium 3102, bythe received data record/judging unit 3103, the encryption unit 3107creates an encryption key “KM” according to the inherent information ofthe recording medium 3102, and the encryption unit 3107 re-encrypts thedigital data “data A” so as to create encrypted digital data “E (KM,dataA)”. When the digital data “dataA” is to be recorded on anotherrecording medium and an encryption key “K′M” is created according to theinherent information of the other recording medium, the encrypteddigital data “E” is encrypted digital data “E(K′M, dataA)”.

The technology of digital data encryption is described in JapaneseLaid-Open Patent Application No. 05-257816. The recording unit 3108records the encrypted digital data that has been received from theencryption unit 3107 on the recording medium 3102. At this time, therecording unit 3108 creates the management information of the recordeddigital data on the recording medium 3102.

FIG. 18 shows an example of management information. Managementinformation 3301 includes title codes 3204, which are the identifiers ofthe recorded digital data, recording start addresses 3302 of therecorded digital data, and recording end addresses 3303 of the recordeddigital data. In the management information 3301, each of the titlecodes 3204 correspond to different recording start addresses 3302, andrecording end addresses 3303.

The management information 3301 is referred to when digital datarecorded on the recording medium 3102 is to be reproduced.

When the recording unit 3108 finishes recording the encrypted digitaldata and the management information on the recording medium 3102, therecording unit 3108 reads the attribute information 3201 that has beenstored in the received data record/judging unit 3103 corresponding tothe recorded digital data, and writes the read attribute information3201 on the recording medium 3102. In addition, the recording unit 3108informs the received data record/judging unit 3103 of the completion ofthe copying, and informs the accounting information recording unit 3109of the title code of the recorded digital data.

When the accounting information recording unit 3109 is informed of thetitle code 3204 by the recording unit 3108, the accounting informationrecording unit 3109 reads the recording charge 3205 of the attributeinformation 3201 corresponding to the title code 3204 that has beenstored in the received data record/judging unit 3103. When theaccounting information recording unit 3109 determines that the recordingcharge 3205 must be paid, the accounting information recording unit 3109records the title code 3204 and the recording charge 3205 on theaccounting information recording medium 3110 as the accountinginformation.

The accounting information recording medium 3110 is composed of a RAMcard and the like. The accounting information of the digital data thathas been downloaded on the recording medium 3102 is recorded by theaccounting information recording unit 3109 on the accounting informationrecording medium 3110.

When the accounting unit 3101 receives an inquiry of a charge from theaccounting center (not illustrated) via the communication unit 3101, theaccounting unit 3111 reads outstanding accounting information that hasbeen recorded on the accounting information recording medium 3110, andinforms the communication unit 3101 of the read outstanding accountinginformation. After informing the communication unit 3101 of theoutstanding accounting information, the accounting unit 3111 records aflag indicating that the accounting center has been informed of theoutstanding accounting information (indicating settlement) on theaccounting information recording medium 3110.

Here, an explanation of operations in the sixth embodiment will be givenwith reference to the flowchart in FIG. 19.

The received data record/judging unit 3103 waits for an indication torecord digital data from the user (step s3402), and determines whetherit is permitted to copy the designated digital data by referring to theattribute information 201 (step s3404). When the received datarecord/judging unit 3103 is not permitted to copy the digital data, thereceived data record/judging unit 3103 has the display unit 3104indicate that the copying is not permitted (step s3406), and then, theprocessing is completed.

When the received data record/judging unit 3103 is permitted to copy thedigital data, the recording medium inherent information obtaining unit3106 obtains the inherent information of the recording medium 3102 thathas been recorded in a secure area on the recording medium 3102, andinforms the encryption unit 3107 of the obtained inherent information(step s3408).

The encryption unit 3107 creates an encryption key according to theinherent information, and re-encrypts the digital data (step s3410).

The recording unit 3108 records the encrypted digital data on therecording medium 3102 (step s3412).

Then, the accounting information recording unit 3109 determines whetherthe recording charge of the recorded digital data must be paid (steps3414). When the recording charge is free, the processing is completed.When the recording charge must be paid, the accounting informationrecording unit 3109 records the accounting information on the accountinginformation recording medium 3110 (step s3416) so as to complete theprocessing.

FIG. 20 shows the structure of a playback apparatus for reproducingdigital data that has been recorded on the recording medium 3102 by thedigital data recording apparatus of the sixth embodiment.

The digital data playback apparatus of the sixth embodiment includes arecording medium 3102, an input operation unit 3501, a reproducinginformation reading unit 3502, a display unit 3503, a recording mediuminherent information obtaining unit 3504, a decryption unit 3505, areproducing unit 3506, an accounting information recording unit 3507,and an accounting information recording medium 3508.

The digital data that has been re-encrypted in the digital datarecording apparatus, the management information 3301, the attributeinformation 3201, and the inherent information for identifying therecording medium 3102 has been recorded on the recording medium 3102.

When the input operation unit 3501 receives an instruction to startreproducing, the input operation unit 3501 provides the reproducinginformation reading unit 3502 with an instruction of initial activation.When the input operation unit 3501 receives the designation of a titlefrom the user, the input operation unit 3501 informs the reproducinginformation reading unit 3502 of the title. Note that an instruction ofan automatic playback mode is given to the reproducing informationreading unit 3502 not only when the initial activation is instructed butalso when the recording medium 3102 is inserted into the digital dataplayback apparatus.

When the reproducing information unit 3502 receives the instruction ofthe initial activation, the reproducing information reading unit 3502reads the attribute information 3201 that has been recorded on therecording medium 3102, and causes the display unit 3503 to display itemsin the attribute information 3201 such as the titles 3202 and players3203.

When the reproducing information reading unit 3502 receives theinstruction of a piece of music or the instruction of the automaticplayback mode from the input operation unit 3501, the reproducinginformation reading unit 3502 determines whether the maximum number ofreproducing 3207 in the attribute information 3201 is equal to orgreater than “1”. When the maximum number of reproducing 3207 is equalto or greater than “1”, the reproducing information reading unit 3502reads the title code 3204 and the encrypted digital data that has beenrecorded from the recording start address 3302 to the recording endaddress 3303, and informs the decryption unit 3505 of the read digitaldata. At this time, the reproducing information reading unit 3502instructs the recording medium inherent information obtaining unit 3504to obtain the inherent information, and informs the accountinginformation recording unit 3507 of the title code 3204 and the chargeper reproduction. Then, when the digital data has been read by thereproducing information reading unit 3502, the reproducing informationreading unit 3502 rewrites the maximum number of reproducing 3207, whichis an item of the attribute information 3201, by decreasing the value ofthe maximum number of reproducing 3207 by one. Note that when themaximum number of reproducing 3207 is “no limit”, the maximum number ofreproducing 3207 is not rewritten.

When the reproducing information reading unit 3502 determines that themaximum number of reproducing is less than “1”, the reproducinginformation reading unit 3502 causes the display unit 3502 to displaythat the digital data cannot be reproduced anymore.

The display unit 3503 is composed of a liquid crystal display and thelike, and displays the list of titles and other information that havebeen read by the reproducing information reading unit 3502. In addition,when the user designates a title of the music data that has beenreproduced the maximum number of times, the display unit 3503 indicatesthat the music data cannot be reproduced anymore.

When the recording medium inherent information obtaining unit 3504 isinstructed by the reproducing information reading unit 3502 to obtainthe inherent information, the recording medium inherent informationobtaining unit 3504 obtains the inherent information, which is theidentifier of the recording medium 3102, from a secure area on therecording medium 3102, and the recording medium inherent informationobtaining unit 3504 informs the decryption unit 3505 of the obtainedinherent information.

When the decryption unit 3505 is informed of the inherent information bythe recording medium inherent information obtaining unit 3504 and whenthe decryption unit 3505 receives the encrypted digital data from thereproducing information reading unit 3502, the decryption unit 3505creates a decryption key according to the inherent information, decryptsthe encrypted digital data, and informs the reproducing unit 3506 of thedecrypted digital data.

When the reproducing unit 3506 is informed of the decrypted digital databy the decryption unit 3505, the reproducing unit 3506 decodes thedigital data to reproduce music. After the reproducing of the music, thereproducing unit 3506 informs the accounting information recording unit3507 that the reproducing is finished.

When the accounting information recording unit 3506 is informed that thereproducing is finished by the reproducing unit 3506, the accountinginformation recording unit 3507 records, as the accounting information,the title code 3204 and the charge per reproduction 3206 that have beenreceived from the reproducing information reading unit 3502 and the dateof reproduction on the accounting information recording medium 3508.Note that when the charge per reproduction 3206 is “free”, the chargeper reproduction 3206 is not recorded.

The accounting information recording medium 3508 is composed of a RAMcard and the like. The accounting information is recorded on theaccounting information recording medium 3508, by the accountinginformation recording unit 3507.

Here, an explanation of operations by the digital data playbackapparatus will be given with reference to the flowchart shown in FIG.21.

First, the user instructs the start of reproduction by using, forinstance, a remote control of the input operation unit 3501, anddesignates a title of music that is displayed by the display unit 3503.The reproducing information reading unit 3502 regards the designation asa requirement to reproduce the music data (digital data) correspondingto the title (step s3602), and determines whether the maximum number ofreproducing 3207 of the music is equal to or greater than “1” byreferring to the attribute information 3201 (step s3604). When themaximum number of reproducing 3207 is less than “1” the reproducinginformation reading unit 3502 causes the display unit 3503 to indicatethat the music data has been reproduced the maximum number of times(step s3606) to thereby complete the processing.

When the maximum number of reproducing 3207 is equal to or greater than“1”, the reproducing information reading unit 3502 reads the encrypteddigital data from the recording medium 3102 and informs the decryptionunit 3505 of the read digital data (step s3608).

Then, the recording medium inherent information obtaining unit 3504obtains the inherent information from the recording medium 3102 andinforms the decryption unit 3505 of the obtained inherent information(step s3610).

The decryption unit 3505 decrypts the encrypted digital data by usingthe inherent information as the decryption key (step s3612).

The reproducing unit 3506 decodes the digital data so as to reproduceand output the music (step s3614).

Then, the accounting information recording unit 3507 determines whetherthe charge per reproduction 3206 must be paid (step s3616). However,when the charge per reproduction 3206 is “free”, the processing iscompleted. When the charge per reproduction 3206 must be paid, theaccounting information recording unit 3507 records the accountinginformation on the accounting information recording medium 3508 (steps3618) to thereby complete the processing.

Seventh Embodiment

FIG. 22 shows the structure of a digital data recording apparatusaccording to a seventh embodiment of the present invention. The digitaldata recording apparatus of the seventh embodiment includes a firstdigital data recording apparatus 3700 and a second digital datarecording/playback apparatus 3710.

The first digital data recording apparatus 3700 includes a firstrecording medium 3701, a communication unit 3101, a received dataprimary record/judging unit 3702, a display unit 3104, an inputoperation unit 3105, a primary recording unit 3703, a received dataread/judging unit 3704, an inherent information obtaining unit 3705, anencryption unit 3706, an accounting information recording unit 3109, anaccounting information recording medium 3110, and an accounting unit3111. The first digital data recording apparatus 3700 is realized by aPC.

The second digital data recording/playback apparatus 3710 includes aninherent information obtaining/transfer unit 3707, a secondary recordingunit 3708, a second recording medium 3709, an input operation unit 3501,a reproducing information reading unit 3502, a display unit 3503, adecryption unit 3505, a reproducing unit 3506, an accounting informationrecording unit 3507, and an accounting information recording medium3508.

Note that the elements of the first digital data recording apparatus3700 and the second digital data recording/playback apparatus 3710 ofthe seventh embodiment that are the same in the digital data recordingapparatus and the digital data playback apparatus of the sixthembodiment have the same reference numbers and explanations of suchelements are not given below.

First, an explanation of the first digital data recording apparatus 3700will be given. The first digital data recording apparatus 3700 isdifferent from the digital data recording apparatus of the sixthembodiment in that the first recording medium 3701 is fixed in the firstdigital data recording apparatus 3700, and in that digital data that hasbeen recorded on the first recording medium 3701 is outputted afterbeing encrypted for secondary recording.

The first recording medium 3701 is composed of a rewritable recordingelement such as a hard disk that is fixed in the first digital datarecording apparatus 3700. Digital data (music data) that has beenreceived by the communication unit 3101 and the management informationof the digital data are recorded on the first recording medium 3701 bythe primary recording unit 3703.

The received data primary record/judging unit 3702 writes attribute datathat is attached to the digital data that has been received by thecommunication unit 3101 in a storage area in an EEPROM. One example ofattribute information that is received in the seventh embodiment isshown in FIG. 23. Attribute information 3801 is different from theattribute information 3201 in the sixth embodiment in that secondaryrecording charges 3802, copy permission (primary) 3803, and copypermission (secondary) are indicated to be a part of the attributeinformation 3801.

The attribute information 3801 shows that neither the primary norsecondary copying is permitted and that only listening in real time ispermitted for a title “music E” having title code “song05”.

When the received data primary record/judging unit 3702 receives aninstruction for secondary recording of the music by the user, thereceived data primary record/judging unit 3702 determines whetherprimary recording is permitted for the music by referring to a copypermission (primary) 3803 item in the attribute information 3801. Whenthe primary recording is not permitted according to the copy permission(primary) 3803 of a particular piece of music, the received data primaryrecord/judging unit 3702 causes the display unit 3104 to indicate thatthe primary recording for the music is not permitted. On the other hand,when the primary recording is permitted, the received data primaryrecord/judging unit 3702 informs the primary recording unit 3703 of thedigital data of the music. Other functions of the received data primaryrecording judging unit are the same as those of the received datarecord/judging unit 3103.

The primary recording unit 3703 records the received digital data on thefirst recording medium 3701. At this time, the management information isalso written as in the case of the recording unit 3108 of the sixthembodiment. Note that while an encryption key is created according tothe inherent information of the recording medium 3102 so as tore-encrypt the digital data in the sixth embodiment, the digital data isnot re-encrypted in the seventh embodiment since the first recordingmedium 3701 is not removable from the first digital data recordingapparatus 3700, i.e., the first recording medium is not used in anotherapparatus in the seventh embodiment.

In addition, when the digital data has been recorded on the firstrecording medium 3701, the primary recording unit 3703 informs thereceived data read/judging unit 3704 of the title code 3805 of therecorded digital data.

When the received data read/judging unit 3704 is informed of the titlecode 3805 by the primary recording unit 3703, the received dataread/judging unit 3704 determines whether the secondary recording of themusic is permitted by referring to the copy permission (secondary) 3804in the attribute information 3801 in the received data primaryrecord/judging unit 3702. When the secondary recording is not permitted,or when the permitted number of times that the data can be recorded isless than “1”, the received data read/judging unit 3704 causes thedisplay unit 3104 to indicate that the secondary recording is notpermitted for the music.

When the secondary recording is permitted, the received dataread/judging unit 3704 refers to the management information (refer toFIG. 18), and reads the digital data of the title code that has beenrecorded on the first recording medium 3701. The received dataread/judging unit 3704 informs the encryption unit 3706 of the digitaldata, and instructs the inherent information obtaining unit 3705 toobtain inherent information.

When the received data read/judging unit 3704 reads the digital data,the received data read/judging unit 3704 decreases the number of timesof the copy permission (secondary) 3804 by “1” in the attributeinformation 3701 that has been stored in the received data primaryrecord/judging unit 3702. For instance, “only once” is changed to “notpermitted”, and “permitted” is not written since the number of times isnot limited.

Note that after the received data read/judging unit 3704 notifies theencryption unit 3706 of the digital data, the received data read/judgingunit 3704 reads the attribute information that has been stored in thereceived data primary record/judging unit 3702.

When the inherent information obtaining unit 3705 is instructed toobtain inherent information by the received data read/judging unit 3704,the inherent information obtaining unit 3705 requests the inherentinformation obtaining/transfer unit 3707 in the second digital datarecording/playback apparatus 3710, which is connected to the firstdigital data recording apparatus 3700, to transmit the inherentinformation. When the inherent information obtaining unit 3705 isinformed of the inherent information by the inherent informationobtaining/transfer unit 3707, the inherent information obtaining unit3705 informs the encryption unit 3706 of the inherent information.

The encryption unit 3706 creates an encryption key according to theinherent information that has been transferred from the inherentinformation obtaining unit 3705, encrypts the digital data that has beentransferred from the received data read/judging unit 3704, and transmitsthe encrypted digital data to the secondary recording unit 3708 in thesecond digital data recording/playback apparatus 3710. After thetransmission of the encrypted digital data, the encryption unit 3706transmits the received attribute information to the secondary recordingunit 3708.

Here, an explanation of the second digital data recording/playbackapparatus 3710 will be given. The second digital data recording/playbackapparatus 3710 is realized by, for instance, a portable headphone stereoapparatus. The second recording medium 3709 is composed of asemiconductor memory such as an IC card that is removable from thesecond digital data recording/playback apparatus 3710.

When the inherent information obtaining/transfer unit 3707 is requiredby the inherent information obtaining unit 3705 in the first digitaldata recording apparatus 3700 to transmit the inherent information, theinherent information obtaining/transfer unit 3707 obtains the mediumidentification information which is inherent in the second recordingmedium 3709 that is recorded on the second recording medium 3709 inadvance and the apparatus identification information which is inherentin the second digital data recording/playback apparatus 3710, and theinherent information obtaining/transfer unit 3707 informs the inherentinformation obtaining unit 3705 of the obtained medium identificationinformation and the apparatus identification information. Meanwhile,when the inherent information obtaining/transfer unit 3707 is instructedto inform of the inherent information by the reproducing informationreading unit 3502, the inherent information obtaining/transfer unit 3707informs the decryption unit 3505 of the obtained medium identificationinformation and the apparatus identification information.

When the secondary recording unit 3708 receives the encrypted digitaldata and the attribute information that has been output from theencryption unit 3706 in the first digital data recording apparatus 3700,the secondary recording unit 3708 records the received encrypted digitaldata and the attribute information on the second recording medium 3709.In addition, the secondary recording unit 3708 records the managementinformation 3301 shown in FIG. 18 on the second recording medium 3709.The decryption unit 3505 creates a decryption key according to themedium identification information and the apparatus identificationinformation that have been transferred from the inherent informationobtaining/transfer unit 3707, and decrypts the encrypted digital datathat has been transferred from the reproducing information reading unit3502 by using the created decryption key. Note that the other parts ofthe structure of the second digital data recording/playback apparatus3710 are almost the same as those of the digital data playback apparatusof the sixth embodiment.

Here, an explanation will be given when the second recording medium 3709is composed of an IC card that is fixed in the second digital datarecording/playback apparatus 3710. In this case, since the secondrecording medium 3709 is only used in the second digital datarecording/playback apparatus 3710, the inherent informationobtaining/transfer unit 3707 does not obtain any medium identificationinformation, and informs the inherent information obtaining unit 3705 ofthe apparatus identification information that the inherent informationobtaining/transfer unit 3707 stores. Meanwhile, the inherent informationobtaining/transfer unit 3707 informs the decryption unit 3505 of theapparatus identification information.

As has been described, it depends on whether the second recording medium3709 in the second digital data recording/playback apparatus 3710 isremovable as to whether an encryption key for encrypting the digitaldata is created according to either the combination of the mediumidentification information and the apparatus identification informationor the apparatus identification information. By doing so, anunauthorized duplication and reproduction of digital data can beprevented.

Here, an explanation of operations in the seventh embodiment will begiven with reference to the flowchart shown in FIG. 24.

First, the received data primary record/judging unit 3702 waits for aninstruction of the secondary recording of digital data from the inputoperation unit 3105 (step s3902), and determines whether the primaryrecording of the digital data is permitted by referring to the attributeinformation 3801 (step s3904). When the primary recording is notpermitted, the received data primary record/judging unit 3702 causes thedisplay unit 3104 to indicate that the primary recording is notpermitted (step s3906) so as to complete the processing.

When the primary recording is permitted, the received data primaryrecord/judging unit 3702 informs the primary recording unit 3703 of thedigital data. The primary recording unit 3703 records the digital dataand the management information on the first recording medium 3701 (steps3908).

Next, the accounting information recording unit 3109 determines whetherthe primary recording is charged or not (step s3910), and records theaccounting information on the accounting information recording medium3110 when the primary recording is charged (step s3912).

Then, the received data read/judging unit 3704 determines whether thesecondary recording of the digital data that has been recorded on thefirst recording medium 3701 is permitted by referring to the attributeinformation 3801 that has been stored in the received data primaryrecord/judging unit 3702 (step s3914). When the secondary recording isnot permitted, the received data read/judging unit 3704 causes thedisplay unit 3104 to indicate that the secondary recording is notpermitted (step s3916) so as to complete the processing.

When the secondary recording is permitted, the received dataread/judging unit 3704 reads the digital data from the first recordingmedium 3701, informs the encryption unit 3706 of the read digital data,and instructs the inherent information obtaining unit 3705 to obtain theinherent information from inherent information obtaining/transfer unit3707 of the second digital data recording playback apparatus 3710. Theinherent information obtaining unit 3705 obtains the inherentinformation, and informs the encryption unit 3706 of the obtainedinherent information (step s3918). The encryption unit 3706 creates anencryption key according to the received inherent information (steps3920), encrypts the received digital data by using the createdencryption key, and outputs the encrypted digital data to the secondaryrecording unit 3708 in the second digital data recording/playbackapparatus 3710.

The secondary recording unit 3708 records the encrypted digital data,the attribute information and the management information on thesecondary recording medium 3709 (step s3922).

The accounting information recording unit 3109 determines whether thesecondary recording is charged (step s3924), and records the accountinginformation on the accounting information recording medium 3110 when thesecondary recording is charged (step s3926) so as to complete theprocessing.

Note that the operations in reproducing the digital data by the seconddigital data recording/playback apparatus 3710 are almost the same asthe operations by the digital data playback apparatus of the sixthembodiment, and therefore, an explanation thereof will be given.

An Other Example of the Seventh Embodiment

While the digital data is encrypted in the seventh embodiment by usingthe encryption key according to the combination of the apparatusidentification information of the second digital data recording/playbackapparatus 3710 and the medium identification information of the secondrecording medium 3709 when the second recording medium 3709 isremovable, the form of encryption is designated by the user (that is, itis designated by the user whether the encryption key is createdaccording to only the medium identification information or thecombination of the medium identification information and the apparatusidentification information) so as to increase the degree of freedom ofusage patterns in this another example of the seventh embodiment. Morespecifically, when the digital data is reproduced with the seconddigital data recording/playback apparatus 3710, the digital data ofmusic that has been recorded on the second recording medium 3709 isencrypted by using the medium identification information and theapparatus identification information at the time of recording. On theother hand, when the digital data is reproduced with another digitaldata playback apparatus (an apparatus that decrypts encrypted digitaldata by using the medium identification information as the decryptionkey), the digital data is encrypted by using the medium identificationinformation at the time of recording. As a result, the form ofencryption can be selected according to the usage pattern.

On the other hand, the secondary recording charges are determinedaccording to the degree of freedom of usage pattern so as to protect thecopyright.

Here, an explanation of the structure of the first digital datarecording apparatus and the second digital data recording/playbackapparatus in the another example of the seventh embodiment will begiven. Note that the functions of the first digital data recordingapparatus and the second digital data recording/playback apparatus inthis example are realized by adding a few functions to those of thefirst digital data recording apparatus 3700 shown in FIG. 22. As aresult, an explanation of only the parts of the structure that aredifferent from the seventh embodiment will be given with reference toFIG. 22, which has been used in the explanation of the seventhembodiment.

FIG. 25 shows a part of attribute information 31001 that is stored inthe received data primary record/judging unit 3702. The attributeinformation 31001 is different from the attribute information 3801 shownin FIG. 23 with regard to the contents of the secondary recordingcharges 3802 and secondary recording charges 31002.

A secondary recording charge 31002 depends on whether the encryption keythat is used in the encryption of the digital data is created accordingto the medium identification information (medium ID) 31003, theapparatus identification information (apparatus ID) 31004, or thecombination of the medium identification information and the apparatusidentification information. When the encryption key has been createdaccording to the medium identification information 31003, the music datacan be reproduced by using the second recording medium 3709 in anotherapparatus and the degree of freedom of the user is increased. As aresult, the secondary recording charge (secondary replication charge) ishigher than when the encryption key has been created according to theapparatus identification information 31004 and the combination of themedium identification information and the apparatus identificationinformation 31005. By doing so, the replication charge is determinedaccording to the usage pattern.

When the inherent information obtaining unit is informed of theapparatus identification information and the medium identificationinformation by the inherent information obtaining/transfer unit 3707,the inherent information obtaining unit 3705 causes the display unit3104 to indicate whether the second recording medium 3709 is used in thesecond digital data recording/playback apparatus 3710 or in anotherapparatus to wait for the user selection.

The user designates the second digital data recording/playback apparatus3710 or another apparatus by using the input operation unit 3501, i.e.,to create the encryption key according to the medium identificationinformation or to create the encryption key according to the combinationof the medium identification information and the apparatusidentification information.

The input operation unit 3501 informs the received data primaryrecord/judging unit 3702 of the user's designation.

When the received data primary record/judging unit 3702 is informed bythe input operation unit 3105 that another apparatus is to be used, thereceived data primary record/judging unit 3702 informs the accountinginformation recording unit 3109 that the secondary recording charge31002 is determined according to the encryption key that is created byusing the medium identification information 31003. On the other hand,when the received data primary record/judging unit 3702 is informed thatonly the second digital data recording/playback apparatus is to be used,the received data primary record/judging unit 3702 informs theaccounting information recording unit 3109 that the secondary recordingcharge 31002 is determined according to the encryption key that iscreated by using the combination of the medium identificationinformation and the apparatus identification information 31005.

When the received data primary record/judging unit 3702 is informed bythe input operation unit 3501 that another apparatus is to be used, theinherent information obtaining unit 3705 informs the encryption unit3706 of only the medium identification information 31003. On the otherhand, when the received data primary record/judging unit 3702 informedby the input operation unit 3501 that only the second digital datarecording/playback apparatus 3710 is to be used, the inherentinformation obtaining unit 3705 informs the encryption unit 3706 of thecombination of the medium identification information and the apparatusidentification information 31005.

When the accounting information recording unit 3109 is informed by theencryption unit 3706 that the encrypted digital data has beentransmitted to the secondary recording unit 3708, the accountinginformation recording unit 3109 refers to the secondary recording charge31002 in the attribute information 31001 that the accounting informationrecording unit 3109 has been informed of by the received data primaryrecord/judging unit 3702, and the accounting information recording unit3105 records the accounting information on the accounting informationrecording medium 3110.

Note that, while it is needless to say, when the second recording medium3709 is a removable DVD-RAM in this example, the encryption key can becreated only according to the identification information which isinherent to the DVD-RAM, the digital data can be re-encrypted by usingthe created encryption key, and the re-encrypted digital data can berecorded as in the case of the sixth embodiment.

Meanwhile, operations in this example are essentially the same as thosein the seventh embodiment, and therefore, an explanation thereof willnot be given.

Note that it is possible to suppose that the accounting informationrecording media 3110 and 3508 are realized by IC cards, for instance,and that the digital data is not recorded and reproduced without settingthe IC cards in the sixth and seventh embodiments and in this example.

In addition, while the digital data that is received by thecommunication unit 3110 has been supposed to be music data in the sixthand seventh embodiments and in this example, the digital data can bevideo data, audio data, character data, and the combination of thosetypes of data.

While the structures of the digital data recording apparatus, thedigital data playback apparatus, and the digital data recording/playbackapparatus are shown in FIGS. 16, 20 and 22, it is possible to record aprogram which realizes the functions of the elements on acomputer-readable recording medium such as a floppy disk, to use thecomputer-readable recording medium in a digital data recording/playbackapparatus that has no function of protecting copyrights, and to have thedigital data recording/playback apparatus have a function of protectingcopyrights.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless such changes and modifications depart fromthe scope of the present invention, they should by construed as beingincluded therein.

1. A digital data recording apparatus for recording digital data on arecording medium, the digital data recorded on the recording mediumbeing reproducible by a playback apparatus and the recording mediumbeing either removable or non-removable from the playback apparatus,said digital data recording apparatus comprising: a communication unitto receive encrypted digital data via a digital network; a decryptionunit to decrypt the encrypted digital data received by saidcommunication unit; an encryption unit including a plurality ofencryption sub-units each of which is to encrypt digital data obtainedby said decryption unit, by using a selected one of a plurality ofencryption methods having different security levels; a recording unit torecord, on the recording medium, encrypted digital data that is obtainedby said encryption unit; and a judging unit to judge whether therecording medium is removable or non-removable from the playbackapparatus, wherein said plurality of encryption sub-units include firstand second encryption sub-units, the first encryption sub-unit is toperform the encryption when the recording medium is judged to beremovable from the playback apparatus, and the second encryptionsub-unit is to perform the encryption when the recording medium isjudged to be non-removable.
 2. The digital data recording apparatusaccording to claim 1, wherein said first encryption sub-unit is toperform the encryption by using an encryption key that is createdaccording to identification information of the recording medium, andsaid second encryption-sub unit is to perform the encryption by using anencryption key that is created according to identification informationof the playback apparatus.
 3. The digital data recording apparatusaccording to claim 1, further comprising an accounting unit to determinean accounting value according to the selection of said one of saidplurality of encryption sub-units and to conduct an accounting processaccording to the determined accounting value.
 4. The digital datarecording apparatus according to claim 1, wherein the security levels ofthe encryption methods used by said plurality of encryption sub-unitsare lower than a security level of an encryption method used inencryption to obtain the encrypted digital data received by saidcommunication unit.
 5. The digital data recording apparatus according toclaim 1, wherein the encrypted digital data received by saidcommunication unit is obtained by using one of a plurality of encryptionmethods having different security levels and the encrypted digital dataincludes attribute information indicating the one of the plurality ofencryption methods used for the encryption, said decryption unitincludes a plurality of decryption sub-units each of which is to decryptthe encrypted digital data that is obtained by using a corresponding oneof the plurality of encryption methods and received by the communicationunit, and said judging unit is to determine the one of the plurality ofencryption methods used to obtain the received encrypted digital dataaccording to the attribute information, and to control said decryptionunit so that a selected one of said plurality of decryption sub-unitscorresponding to the determined one of the plurality of encryptionmethods decrypts the encrypted digital data.
 6. The digital datarecording apparatus according to claim 5, further comprising anaccounting unit to determine an accounting value according to theselection of said one of said decryption sub-units and the selection ofsaid one of said encryption sub-units, and to conduct an accountingprocess according to the determined accounting value.
 7. A digital datarecording method for recording digital data on a recording medium, thedigital data recorded on the recording medium being reproducible by aplayback apparatus and the recording medium being either removable ornon-removable from the playback apparatus, said digital data recordingmethod comprising: a step of receiving encrypted digital data via adigital network; a step of decrypting the encrypted digital datareceived in said receiving step; a step of encrypting digital dataobtained in said decrypting step, using a selected one of a plurality ofencryption methods having different security levels; a step ofrecording, on the recording medium, encrypted digital data that isobtained in said encrypting step; and a step of judging whether therecording medium is removable or non-removable from the playbackapparatus, wherein said encrypting step includes: a first encryptingsub-step of encrypting the digital data obtained in said decryptingstep, when the recording medium is judged to be removable from theplayback apparatus; and a second encrypting sub-step of encrypting thedigital data obtained in said decrypting step, when the recording mediumis judged to be non-removable.
 8. A computer-readable program recordingmedium storing a program for causing a computer to record digital dataonto a digital-data recording medium, the digital data recorded on thedigital-data recording medium being reproducible by a playback apparatusand the digital-data recording medium being either removable ornon-removable from the playback apparatus, said program comprising codeoperable to cause the computer to perform: a step of receiving encrypteddigital data via a digital network; a step of decrypting the encrypteddigital data received in said receiving step; a step of encryptingdigital data obtained in said decrypting step, using a selected one of aplurality of encryption methods having different security levels; a stepof recording, on the digital-data recording medium, encrypted digitaldata that is obtained in said encrypting step; and a step of judgingwhether the digital-data recording medium is removable or non-removablefrom the playback apparatus, wherein said encrypting step includes: afirst encrypting sub-step of encrypting the digital data obtained insaid decrypting step, when the digital-data recording medium is judgedto be removable from the playback apparatus; and a second encryptingsub-step of encrypting the digital data obtained in said decryptingstep, when the digital-data recording medium is judged to benon-removable.